Degraded microarchitecture by low trabecular bone score is associated with prevalent vertebral fractures in patients with systemic lupus erythematosus

Osteoporosis and fracture risk are multifactorial in patients with inflammatory rheumatic diseases

Patients with inflammatory rheumatic and musculoskeletal diseases (iRMDs) such as rheumatoid arthritis, connective tissue diseases, vasculitides and spondyloarthropathies are at a higher risk of osteoporosis and fractures than are individuals without iRMDs. Research and management recommendations for osteoporosis in iRMDs often focus on glucocorticoids as the most relevant risk factor, but they largely ignore disease-related and general risk factors. However, the aetiopathogenesis of osteoporosis in iRMDs has many facets, including the negative effects on bone health of local and systemic inflammation owing to disease activity, other iRMD-specific risk factors such as disability or malnutrition (for example, malabsorption in systemic sclerosis), and general risk factors such as older age and hormonal loss resulting from menopause. Moreover, factors that can reduce fracture risk, such as physical activity, healthy nutrition, vitamin D supplementation and adequate treatment of inflammation, are variably present in patients with iRMDs. Evidence relating to general and iRMD-specific protective and risk factors for osteoporosis indicate that the established and very often used term 'glucocorticoid-induced osteoporosis' oversimplifies the complex inter-relationships encountered in patients with iRMDs. Osteoporosis in these patients should instead be described as 'multifactorial'. Consequently, a multimodal approach to the management of osteoporosis is required. This approach should include optimal control of disease activity, minimization of glucocorticoids, anti-osteoporotic drug treatment, advice on physical activity and nutrition, and prevention of falls, as well as the management of other risk and protective factors, thereby improving the bone health of these patients.

Update on the clinical use of trabecular bone score (TBS) in the management of osteoporosis: results of an expert group meeting organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), and the International Osteoporosis Foundation (IOF) under the auspices of WHO Collaborating Center for Epidemiology of Musculoskeletal Health and Aging

PURPOSE

Trabecular bone score (TBS) is a grey-level textural measurement acquired from dual-energy X-ray absorptiometry lumbar spine images and is a validated index of bone microarchitecture. In 2015, a Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) published a review of the TBS literature, concluding that TBS predicts hip and major osteoporotic fracture, at least partly independent of bone mineral density (BMD) and clinical risk factors. It was also concluded that TBS is potentially amenable to change as a result of pharmacological therapy. Further evidence on the utility of TBS has since accumulated in both primary and secondary osteoporosis, and the introduction of FRAX and BMD T-score adjustment for TBS has accelerated adoption. This position paper therefore presents a review of the updated scientific literature and provides expert consensus statements and corresponding operational guidelines for the use of TBS.

METHODS

An Expert Working Group was convened by the ESCEO and a systematic review of the evidence undertaken, with defined search strategies for four key topics with respect to the potential use of TBS: (1) fracture prediction in men and women; (2) initiating and monitoring treatment in postmenopausal osteoporosis; (3) fracture prediction in secondary osteoporosis; and (4) treatment monitoring in secondary osteoporosis. Statements to guide the clinical use of TBS were derived from the review and graded by consensus using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

A total of 96 articles were reviewed and included data on the use of TBS for fracture prediction in men and women, from over 20 countries. The updated evidence shows that TBS enhances fracture risk prediction in both primary and secondary osteoporosis, and can, when taken with BMD and clinical risk factors, inform treatment initiation and the choice of antiosteoporosis treatment. Evidence also indicates that TBS provides useful adjunctive information in monitoring treatment with long-term denosumab and anabolic agents. All expert consensus statements were voted as strongly recommended.

CONCLUSION

The addition of TBS assessment to FRAX and/or BMD enhances fracture risk prediction in primary and secondary osteoporosis, adding useful information for treatment decision-making and monitoring. The expert consensus statements provided in this paper can be used to guide the integration of TBS in clinical practice for the assessment and management of osteoporosis. An example of an operational approach is provided in the appendix. This position paper presents an up-to-date review of the evidence base, synthesised through expert consensus statements, which informs the implementation of Trabecular Bone Score in clinical practice.

Trabecular bone score in rheumatic disease

Patients with rheumatic diseases (RD) are at high risk of osteoporosis (OP) and osteoporotic fractures. The Trabecular bone score (TBS) is a relatively novel method of assessing bone quality, which independently predicts fracture risk regardless of bone mineral density (BMD). A lower TBS in patients with RD compared to controls is shown in most studies concerning TBS and RD. The data obtained indicate that TBS predicts fractures better in RD, especially in patients receiving glucocorticoids, than BMD or the FRAX algorithm. TBS degradation has been associated with disease activity in ankylosing spondylitis, systemic sclerosis, and rheumatoid arthritis in a few studies. However, there is little data in the literature on the effect of rheumatic disease therapy and OP treatment in patients with RD on predictive ability of TBS for incident fracture.

Bone Involvement in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a wide variability of clinical manifestations due to the potential involvement of several tissues and internal organs, with a relapsing and remitting course. Dysregulation of innate and adaptive immune systems, due to genetic, hormonal and environmental factors, may be responsible for a broad spectrum of clinical manifestations, affecting quality of life, morbidity and mortality. Bone involvement represents one of the most common cause of morbidity and disability in SLE. Particularly, an increased incidence of osteoporosis, avascular necrosis of bone and osteomyelitis has been observed in SLE patients compared to the general population. Moreover, due to the improvement in diagnosis and therapy, the survival of SLE patient has improved, increasing long-term morbidities, including osteoporosis and related fractures. This review aims to highlight bone manifestations in SLE patients, deepening underlying etiopathogenetic mechanisms, diagnostic tools and available treatment.

Trabecular Bone Score in Rheumatic Disease

PURPOSE OF REVIEW

Patients with rheumatic disease are at high risk of low bone mass and osteoporotic fracture. Trabecular bone score (TBS), derived from lumbar spine dual-energy x-ray absorptiometry (DXA), is a novel measure of bone texture that independently predicts fracture risk. This review examines the role of TBS in rheumatic disease including fracture prediction.

RECENT FINDINGS

Most studies concerning TBS and rheumatic disease are cross-sectional, with consistent evidence of lower TBS in patients with rheumatic disease compared to controls. Recent studies have shown association and predictive ability of TBS for prevalent fracture, and the few longitudinal studies showed predictive ability of TBS for incident fracture. TBS in ankylosing spondylitis is of interest given the high rates of vertebral fracture and technical difficulty with lumbar spine bone mineral density. TBS degradation has been associated with disease activity in ankylosing spondylitis, systemic sclerosis, and rheumatoid arthritis. Glucocorticoid exposure is associated with lower TBS, and predicts prevalent fracture, in patients with rheumatic conditions.

Discriminative ability of trabecular bone score over bone mineral density for vertebral and fragility fracture in patients treated with long-term and low-dose glucocorticoid

AIM

To evaluate the ability of the trabecular bone score (TBS) to discriminate vertebral fracture (VF) and fragility fracture (FF) in patients with chronic inflammatory rheumatic diseases on long-term and low-dose glucocorticoid (GC) treatment and those without exposure to GC.

METHODS

This study assessed TBS and bone mineral density (BMD) in chronic GC users, defined as ≥2.5 mg/d of prednisone for >3 months (n = 89, mean age: 62.5 ± 11 years), and in controls (n = 59, mean age: 60.3 ± 9.6 years). Osteoporosis risk factors, radiographs of the thoracolumbar spine, non-VF history, osteoporosis drugs, and current/cumulative GC doses were collected. Patients were classified as high (TBS <1.23), intermediate (1.23-1.31), or low risk (>1.31), according to the fracture risk based on a recent meta-analysis.

RESULTS

The mean current dose and duration of GC treatment were 3.9 ± 1.9 mg/d and 3.9 ± 4.2 years, respectively. The prevalence of VF was significantly higher in chronic GC users than in controls (20.2% vs 5.1%, P = .010), although the prevalence of non-VF was similar (11.2% vs 5.1%). The GC group had significantly lower L1-L4 TBS and femur total BMD than did the controls (all with P < .01) without significantly different lumbar BMD. TBS (<1.31) showed a higher sensitivity for patients with VF and FF (83.3% and 81.8%, respectively) than with densitometric osteoporosis in the GC group (61.1% and 59.1%, respectively). Using the receiver operating characteristic curve, TBS <1.31 showed better diagnostic accuracy than TBS <1.23 and BMD in chronic GC users.

CONCLUSION

TBS is more sensitive than BMD in detecting VF and FF in chronic GC users, even at a lower dose.

Traditional and Non-traditional Risk Factors for Osteoporosis in CKD

Osteoporosis is a state of bone fragility with reduced skeletal resistance to trauma, and consequently increased risk of fracture. A wide range of conditions, including traditional risk factors, lifestyle choices, diseases and their treatments may contribute to bone fragility. It is therefore not surprising that the multi-morbid patient with chronic kidney disease (CKD) is at a particularly high risk. CKD is associated with reduced bone quantity, as well as impaired bone quality. Bone fragility in CKD is a composite of primary osteoporosis, accumulation of traditional and uremia-related risk factors, assaults brought on by systemic disease, and detrimental effects of drugs. Some risk factors are modifiable and represent potential targets for intervention. This review provides an overview of the heterogeneity of bone fragility in CKD.

Beyond Bone Mineral Density: A New Dual X-Ray Absorptiometry Index of Bone Strength to Predict Fragility Fractures, the Bone Strain Index

For a proper assessment of osteoporotic fragility fracture prediction, all aspects regarding bone mineral density, bone texture, geometry and information about strength are necessary, particularly in endocrinological and rheumatological diseases, where bone quality impairment is relevant. Data regarding bone quantity (density) and, partially, bone quality (structure and geometry) are obtained by the gold standard method of dual X-ray absorptiometry (DXA). Data about bone strength are not yet readily available. To evaluate bone resistance to strain, a new DXA-derived index based on the Finite Element Analysis (FEA) of a greyscale of density distribution measured on spine and femoral scan, namely Bone Strain Index (BSI), has recently been developed. Bone Strain Index includes local information on density distribution, bone geometry and loadings and it differs from bone mineral density (BMD) and other variables of bone quality like trabecular bone score (TBS), which are all based on the quantification of bone mass and distribution averaged over the scanned region. This state of the art review illustrates the methodology of BSI calculation, the findings of its in reproducibility and the preliminary data about its capability to predict fragility fracture and to monitor the follow up of the pharmacological treatment for osteoporosis.

What Role Does Trabecular Bone Score Play in Chronic Inflammatory Rheumatic Diseases?

Patients suffering from rheumatic inflammatory diseases, e.g., systemic sclerosis, rheumatoid arthritis, and ankylosing spondylitis, are at risk of low bone mass. Dual-energy X-ray Absorptiometry (DXA) is the traditional radiological measurement technique for bone mineral density (BMD). The recently developed trabecular bone score (TBS) enhances the skeletal information provided by standard BMD. It re-analyzes the spatial dynamics of pixel intensity changes in lumbar spine DXA images, defining a quantitative index, characterizing trabecular bone microarchitecture. It has been demonstrated that low TBS values are associated with an increased incidence of fractures in patients with rheumatic diseases. These methods used together for bone damage evaluation can be of value to identify individuals who will potentially fracture. The main scientific literature on the clinical aspects of osteoporosis, including the use of TBS in evaluating this pathology, are herein reported aimed at shedding light on the role trabecular bone score plays in chronic inflammatory rheumatic diseases.

Trabecular Bone Score and Bone Quality in Systemic Lupus Erythematosus Patients

Background: Systemic lupus erythematosus (SLE) patients run a higher risk of having low bone mass due to multifactorial events that include physical inactivity, persistent inflammation, low vitamin D levels, and glucocorticoid treatment. This study aimed at obtaining a comparison between bone involvement in SLE patients and healthy matched subjects (HS).

Methods: A total of 40 SLE females (average age 54.1 ± 16.3 years) and 40 age–gender matched HS (average age 54.2 ± 15.9 years) were enrolled after having obtained informed written consent. Bone mineral density (BMD, g/cm²) of the lumbar spine (L1–L4) was analyzed by a dual-energy X-ray absorptiometry (DXA) scan (GE, Lunar Prodigy). The lumbar spine trabecular bone score (TBS) was derived for each spine DXA examination by the TBS index (TBS iNsight Medimaps).

Results: The lumbar spine TBS score was statistically significantly lower in SLE patients than in HS (0.797 ± 0.825 vs. 1.398 ± 0.207, p < 0.001, as was BMD (p < 0.001) in all areas examined.

Conclusions: SLE is associated with significant low bone mass as evidenced by DXA and TBS. This study emphasizes the importance of using DXA and TBS in the evaluation of the different aspects of bone architecture.